Methods and apparatus to power an exercise machine

ABSTRACT

Methods and apparatus to power an exercise machine are disclosed herein. An example exercise machine includes a power receiver to measure a power output by a generator that is to convert movement of a moveable part into electric power, the power receiver is to calculate a rotations per minute of the moveable part. A mode controller is to calculate a power supply duty cycle based on the power output by the generator, the rotations per minute of the moveable part, and a user selected wattage. A power output controller is to control power provided to a console of the exercise machine based on the power supply duty cycle.

RELATED APPLICATION

This patent arises from a continuation of U.S. patent application Ser.No. 15/412,851, filed on Jan. 23, 2017, and entitled “METHODS ANDAPPARATUS TO POWER AN EXERCISE MACHINE”, which is a divisional of U.S.patent application Ser. No. 14/026,928, filed on Sep. 13, 2013, andentitled “METHODS AND APPARATUS TO POWER AN EXERCISE MACHINE,” whichclaims the benefit of U.S. Provisional Patent Application Ser. No.61/701,400, which was filed on Sep. 14, 2012. U.S. patent applicationSer. No. 15/412,851, U.S. patent application Ser. No. 14/026,928 andU.S. Provisional Patent Application Ser. No. 61/701,400 are herebyincorporated herein by reference in their entireties.

FIELD OF THE DISCLOSURE

This disclosure relates generally to exercise machines and, moreparticularly, to methods and apparatus to power an exercise machine.

BACKGROUND

Exercise machines such as stationary bikes, elliptical trainers, andsteppers typically include a console that allows the user to selectexercise programs and provide other functions such as, for example,entertainment, workout statistics, etc. Some exercise machines includeadditional electronics such as a television and/or provide power toother external devices such as smartphones, tablets, etc. Operating theconsole and/or the additional electronics requires additional electricalpower that must be provided to the exercise machine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example exercise apparatus.

FIG. 2 is a block diagram of the example exercise machine of FIG. 1

FIG. 3 is a block diagram of an example generator brake controller ofthe illustrated example of FIG. 2.

FIG. 4 is a circuit diagram illustrating an example implementation ofthe example exercise machine of FIG. 2.

FIG. 5 is a diagram illustrating three example regions of operation ofthe example generator brake controller of FIG. 3.

FIG. 6 is a flowchart representative of an example method that may beperformed to implement the example generator brake controller of FIG. 3using three regions of operation.

FIGS. 7A, 7B, 7C, and 7D are a flowchart representative of an examplemethod that may be performed to implement the example generator brakecontroller of FIG. 3 using a single region of operation.

FIG. 8 is a block diagram of an example processor platform that mayexecute, for example, machine-readable instructions to implement theexample method of FIG. 6, machine-readable instructions to implement theexample method of FIGS. 7A, 7B, 7C, and 7D, and/or the example generatorbrake controller of FIG. 3.

DETAILED DESCRIPTION

Exercise machines that provide consoles to users power those consoleswith various power sources. Exercise machines are traditionally poweredby an external power source (e.g., a power outlet and/or a poweradapter). Some exercise machines are self-powered and, in that case, thepower used to operate the console is generated by the user. An exampleself-powered exercise machine includes an alternator and/or a generatoras part of a load device that enables generation of electricity to powerthe console. Some self-powered systems include a battery to providecontinuous power to the console (e.g., if there is a pause in theworkout).

The power available to the console in a self-powered exercise machine islimited by the electrical power generated by the user. Consoles thatinclude televisions and other advanced features may require asignificant amount electrical power that the user may not be able togenerate. For example, some users (e.g., elderly persons, rehabilitationpatients, etc.) may need to exercise at a very low level and may notgenerate enough electrical power to operate the console. In someexamples, the self-powered exercise machine receives power from anexternal power supply that powers the exercise machine when the usergenerates an insufficient amount of electrical power.

In the examples disclosed herein, a hybrid mode is used to power theconsole using electrical power generated by the user and receivedsimultaneously from a power supply. When the user is generatingsufficient power (e.g., a power level over a threshold), the powergenerated by the user is delivered to the console rather than from thepower supply. In some examples, light users (e.g., rehabilitationpatients, elderly persons, etc.) may not achieve the threshold level ofpower. However, other users may power the console through their exerciseefforts.

Combining power from the power supply and generated by the user enablesless power to be drawn from external power sources (e.g., commercialelectricity). Accordingly, the amount of electrical power used tooperate the exercise machine and, consequently, the costs of electricityused to operate the exercise machine are reduced. In the setting of agym and/or workout center, the electricity and/or cost savings may besignificant. Furthermore, in some examples, electricity generated by auser on a first exercise machine may be used to power a console and/orother electronics on a second exercise machine (e.g., when there is asurplus of user-generated electricity at the first exercise machine).

The examples disclosed herein enable a user to select a level of effort(e.g., a workout resistance) independent of the power draw required bythe console and/or additional electronic devices (e.g., a television, anApple iPod™, a smartphone, a tablet computer, etc.). Resistance levelsprovided to the user (e.g., to simulate a more strenuous workout) arecontrolled to ensure that the user still feels the same amount ofresistance regardless of the electrical power that is generated by theuser.

In the examples disclosed herein, electricity or electrical power isreceived from a first power supply (e.g., a power supply external to theexercise machine) and is provided in parallel with electrical powerreceived from a second power supply (e.g., a generator that generateselectricity based on user input) to power electronics of the exercisemachine (e.g., a console, a television). In addition to the secondsupply, an additional load is added to the generator when a higher levelof exercise is selected by the user than would be delivered by supplyingthe full power to the electronics of the exercise machine. The output ofthe second power supply is controlled to provide all or part of thepower to the electronics of the exercise machine and/or to provide allor part of the resistance to the user.

FIG. 1 illustrates an example exercise machine 100. In the illustratedexample, the exercise machine 100 is a stationary bike. However, anyother type of exercise machine 100 may additionally or alternatively beused such as, for example, an elliptical trainer, a stepper, etc. Theexercise machine 100 of the illustrated example receives electricalpower from a power supply 110. The power supply 110 receives electricityfrom a commercial power source 115 (e.g., an electrical outlet). In theillustrated example, the power supply 110 is separate from (e.g.,external to) the exercise machine 100. However, in some examples, thepower supply 110 may be integral and/or internal to the exercise machine100.

In the illustrated example, the exercise machine 100 includes a console120. The console 120 of the illustrated example of FIG. 1 is atouchscreen display. However any other type(s) and/or format(s) ofconsoles may additionally or alternatively be used. In the illustratedexample, the console 120 functions as a television that may be used to,for example, entertain a user during a workout. In some examples, theconsole 120 enables a user to plug in one or more optional attachabledevice(s) 122 such as, for example, a television, a smartphone, a tabletpc, an mp3 player, a computer display, etc. In some examples, theconsole 120 provides power to these attachable external device(s) 122using a power converter such as, for example, a twelve-volt buckconverter. However, any other type and/or number of converters mayadditionally or alternatively be used. For example, a five voltconverter may be used to provide power to a device connected via aUniversal Serial Bus (USB) port and/or USB cable.

FIG. 2 is a block diagram of the example exercise machine 100 of FIG. 1.The exercise machine 100 includes a generator brake 210, a generatorbrake controller 220, and the console 120. In the illustrated example,the exercise machine 100 includes the power supply 110. However, asdescribed above, the power supply 110 may be internal and/or externalwith respect to the exercise machine 100.

The generator brake 210 interfaces with the user of the exercise machine100 to receive movement of the user and convert that movement ormechanical power into electricity or electrical power. In theillustrated example, the generator brake 210 receives movement of theuser via a moveable part such as, for example, a pedal 101. Furthermore,the generator brake 210 provides a variable resistance level to theuser, enabling varying degrees of input energy required by the userduring a workout. In some examples, the generator brake 210 may beimplemented using a generator (e.g., a high efficiency generator) loadedby a resistor that may be controlled using a pulse-width modulated (PWM)signal to control the resistance felt by the user. In the illustratedexample, the generator brake 210 is implemented by a generator loaded bya resistor. However, the generator brake 210 may be implemented in anyother fashion such as, for example, an automotive alternator with aresistive load, a permanent magnet generator with a resistive load, etc.

The generator brake controller 220 of the illustrated example isimplemented by a processor executing instructions but could,alternatively, be implemented by an application specific integratedcircuit(s) (ASIC(s)), programmable logic device(s) (PLD(s)) and/or fieldprogrammable logic device(s) (FPLD(s)), or other analog and/or digitalcircuitry. In the illustrated example, the generator brake controller220 measures power output by the generator brake 210, controls theresistance level of the generator brake 210, and provides power to theconsole 120.

FIG. 3 is a block diagram of an example generator brake controller 220of the illustrated example of FIG. 2. The example generator brakecontroller 220 of FIG. 3 includes a generator power receiver 320, abrake controller 330, a mode controller 340, and a power outputcontroller 350.

The generator power receiver 320 of the illustrated example of FIG. 3 isimplemented by a three-phase rectifier with an output capacitor, aresistor divider, and a square wave converter. The operation of thegenerator power receiver 320 is described in detail in connection withFIG. 4.

The brake controller 330 of the illustrated example of FIG. 3 isimplemented by a switch that controls current flowing through a brake(referred to herein as a brake current) of the generator brake 210. Inthe illustrated example, the switch is implemented by a metal oxidesemiconductor field effect transistor (MOSFET). However, the switch maybe implemented by any other type of switch such as, for example, atransistor, a relay, a potentiometer, a rheostat, etc. In theillustrated example, the brake current is controlled by switching theswitch using a pulse width modulated signal received from the modecontroller. In the illustrated example, the brake current is monitoredto provide a closed loop control of the resistance of the exercisemachine experienced by the user.

The mode controller 340 of the illustrated example of FIG. 3 isimplemented by a processor executing instructions but could,alternatively, be implemented by an ASIC, PLD, FPLD, or other analogand/or digital circuitry. In the illustrated example, the modecontroller measures power output by the generator brake 210, controlsthe resistance level of the generator brake 210 via the brake controller330, and provides power to the console 120 via the power outputcontroller 350.

The power output controller 350 of the illustrated example of FIG. 3 isimplemented by a first rectifier and a second rectifier positioned in awired-OR configuration. In the illustrated example, both the firstrectifier and the second rectifier are Schottky diodes. However, anyother type(s) and/or configuration(s) of rectifier may additionally oralternatively be used such as, for example, a diode, a transistor, aswitch, a synchronous rectifier, etc. In the illustrated example, thefirst rectifier is coupled to the power supply 110 and the secondrectifier is coupled to the generator power receiver 320 via an isolatedflyback converter. The isolated flyback converter of the power outputcontroller 350 receives a pulse width modulated signal from the modecontroller 340. While in the illustrated example, the example poweroutput controller 350 is implemented using two rectifiers in a wired-ORconfiguration and an isolated flyback converter 435, any otherconfiguration of the example power output controller 350 mayadditionally or alternatively be used. For example, the power outputcontroller 350 may be implemented by one or more transistors such as,for example, field effect transistors (FETs), a buck-boost converter, anon-isolated flyback converter, etc.

FIG. 4 is a circuit diagram 400 illustrating an example implementationof the example exercise machine 100 of FIG. 2. The circuit diagram 400includes the power supply 110, the generator brake 210, the generatorbrake controller 220, and the console 120. In the illustrated example ofFIG. 4, the generator brake controller 220 includes the generator powerreceiver 320, the brake controller 330, the mode controller 340, and thepower output controller 350.

The generator brake 210 includes a generator 405, and a brake 410. Thegenerator 405 is a three-phase permanent magnet outer rotor typegenerator. However, any other type of generator may additionally oralternatively be used. The rotor of the generator includes a flywheel.The brake 410 is an electromagnetic brake that is attached to theflywheel, and adds resistance for the user. The electricity to power thebrake 410 is received from the generator power receiver 320, whichrectifies the three-phase output of the generator 405. Accordingly, theelectricity used to power the brake 410 is generated by the generator405.

As described above, the generator power receiver 320 includes athree-phase rectifier 415, a resistor divider 420, and a square waveconverter 425. The three-phase rectifier 415 receives three-phase powerfrom the generator brake 210 and creates a rectified output. Therectified output is used to power the brake 410. The rectified output isalso provided to the power output controller 350. The resistor divider420 reduces the rectified output of the three-phase rectifier 415 sothat the rectified output can be measured by the mode controller 340.The square wave converter 425 of the generator power receiver 320converts one of the three phases received from the generator 405 so thatthe mode controller 340 can accurately measure the rotations per minuteof the rotor of the generator 405.

In the illustrated example, the circuit 400 further includes an isolatedkeep-alive direct current (DC) power supply 430. The isolated keep-aliveDC power supply 430 receives power from the output of the power outputcontroller 350. Accordingly, when no power is generated by the generator405, the generator brake controller 220 can remain powered via the powerprovided by the power supply 110.

In the illustrated example, the mode controller 340 provides a pulsewidth modulated signal to the isolated flyback converter 435. Theisolated flyback converter 435 of the power output controller 350 setsthe power transmitted from the generator 405 to the console 120 based onthe pulse width modulated signal received from the mode controller 340.While in the illustrated example, a pulse width modulated signal usused, any other type of control signal may additionally or alternativelybe used such as, for example, a digital control signal, an analogcontrol signal, etc.

If the power output from the generator power receiver 320 and receivedby the isolated flyback converter 435 is sufficiently lower than thepower received from the power supply 110, the isolated flyback converter435 is set to enable power to be transmitted from the power supply 110to the console 120. Conversely, if the power output from the generatorpower receiver 320 and received by the isolated flyback converter 435 issufficiently higher than the power received from the power supply 110,the isolated flyback converter 435 is set to transmit power from thegenerator power receiver 320 to the console 120.

When the power received from the power supply 110 and the generatorpower receiver 320 are approximately equal (e.g., within a thresholdpercentage of each other, such as, for example, thirty percent), thepower provided to the console 120 is sourced from both the power supply110 and the generator power receiver 320. In the illustrated example,the power sourced from the power supply 110 and the generator powerreceiver 320 is not equal. Slight changes of the generator powerreceiver 320 reference voltage will increase or decrease the amount ofload current provided by the generator power receiver 320.

In the illustrated example, the mode controller 340 uses two controlloops to regulate the power provided to the console 120. The primarycontrol loop regulates the load torque on the generator 405 bycontrolling the brake current. The torque can be calculated using thebrake current and power supply current. However, second order effectsmakes deriving a closed form solution to this relationship difficult. Inthe illustrated example, the torque is calculated using the followingequation:

Torque=k0+kps*i_ps+k2*i_brakê2+k1*i_brake

In the illustrated example, k0, kps, k1, k2 are constants; i_ps is thecurrent provided from the three-phase rectifier 415 to the isolatedflyback converter 420, and i_brake is the brake current. In exampleswhere a different configuration of the generator brake 210 is used, thetorque equation may be varied so that a proper amount of resistance isexperienced by the user during the workout. While in the illustratedexample a second order equation is used to calculate the torque, inother examples other equations and/or formulas may additionally oralternatively be used.

The mode controller 340 of the illustrated example implements a digitalproportional integral (PI) control and minimizes torque error using thefollowing equation:

Error_torque(t)=torque_ref(t)−torque_cal(t)

In the above formula, torque_ref is a constant times the power generatedby the user divided by an RPM. The power generated by the user ismeasured in watts. The RPM is the rotational speed (revolutions perminute) of the rotor of the generator 405 as measured via the squarewave generator 425.

A second PI control loop is implemented by the mode controller 340 tominimize the power supply current error signal using the followingequation:

Error_ips=ips_ref−ips

In the above formula, ips_ref is the desired amount of current to bedelivered by the power supply. In some examples, the reference can beset to zero where it is desired to disable hybrid control such as, forexample, low rpm scenarios, low generator voltage scenarios, and/or verylight user power scenarios.

FIG. 5 is a diagram illustrating three example modes of operation of theexample generator brake controller of FIG. 3. In the illustrated exampleof FIG. 5, a horizontal line 505 represents the target power produced bythe user in watts (P_(USER TARGET)). The left side of the horizontalline 505 represents a low wattage, while the right side of thehorizontal line 505 represents a high wattage.

A first vertical line represents a lower threshold 510. In theillustrated example, the lower threshold 510 is equivalent to seventenths of the total power load (P_(L)) divided by a flyback power supplyefficiency (N_(PS)). In the illustrated example the P_(L) represents thetotal power of the console 120 including any attachments such as, forexample, a television, a tablet computer, a smartphone, etc. The N_(PS)equals P_(L) divided by the flyback power supply input power (P_(PS)).The P_(PS) equals the rectified generator output voltage (V_(BUS)) timesthe flyback power supply input current (I_(PS)). A second vertical linerepresents an upper threshold 515. The upper threshold 515 is equivalentto one and three tenths of the P_(L) divided by N_(PS).

When P_(USER TARGET) is less than the lower threshold 510, the modecontroller 340 sets the flyback power supply input current (I_(PS)) 520equal to the resistance felt by the user measured in watts (P_(USER))divided by the V_(BUS). When P_(USER TARGET) is greater than the lowerthreshold 510 and less than the upper threshold 515, the mode controller340 sets the flyback power supply input current (I_(PS)) 530 equal toseven tenths of the resistance felt by the user measured in watts(P_(USER)) divided by the V_(BUS). When P_(USER TARGET) is greater thanthe upper threshold 515, the mode controller 340 sets the flyback powersupply input current (I_(PS)) 540 equal to the resistance felt by theuser measured in watts (P_(USER)) divided by the V_(BUS).

When P_(USER TARGET) is less than the lower threshold 510, the modecontroller 340 sets the target brake current (I_(B TARGET)) to zero 525.When P_(USER TARGET) is greater than the lower threshold 510 and lessthan the upper threshold 515, the mode controller 340 sets the I_(B)TARGET to a function of P_(USER) TARGET, an RPM of the rotor of thegenerator 405, and I_(PS) 535. In the illustrated example of FIG. 5, thebrake current (I_(B TARGET)) is calculated using the torque calculationsdescribed above. When P_(USER TARGET) is greater than the upperthreshold 515, the mode controller 340 sets the I_(B TARGET) to afunction of P_(USER) TARGET, an RPM of the rotor of the generator 405,and I_(PS) 545.

While an example manner of implementing the example generator brakecontroller 220 of FIG. 2 has been illustrated in FIGS. 3 and/or 4, oneor more of the elements, processes, and/or devices illustrated in FIGS.3 and/or 4 may be combined, divided, re-arranged, omitted, eliminated,and/or implemented in any other way. Further, the example generatorpower receiver 320, the brake controller 330, the mode controller 340,the power output controller 350, and/or, more generally, the examplegenerator brake controller 220 of FIGS. 2, 3, and/or 4 may beimplemented by hardware, software, firmware, and/or any combination ofhardware, software, and/or firmware. Thus, for example, any of theexample generator power receiver 320, the brake controller 330, the modecontroller 340, the power output controller 350, and/or, more generally,the example generator brake controller 220 of FIGS. 2, 3, and/or 4 couldbe implemented by one or more circuit(s), programmable processor(s),application specific integrated circuit(s) (ASIC(s)), programmable logicdevice(s) (PLD(s)) and/or field programmable logic device(s) (FPLD(s)),etc. When any of the apparatus or system claims of this patent are readto cover a purely software and/or firmware implementation, at least oneof the example generator power receiver 320, the brake controller 330,the mode controller 340, and/or the power output controller 350 arehereby expressly defined to include a tangible computer readable mediumsuch as a memory, DVD, CD, Blu-ray, etc. storing the software and/orfirmware. Further still, the example generator brake controller 220 ofFIGS. 2, 3, and/or 4 may include one or more elements, processes and/ordevices in addition to, or instead of, those illustrated in FIGS. 3and/or 4, and/or may include more than one of any or all of theillustrated elements, processes, and devices.

Flowcharts representative of example methods 600 and/or 700 forimplementing the generator brake controller 220 of FIGS. 2, 3, and/or 4is shown in FIGS. 6, 7A, 7B, 7C, and/or 7D. In this example, the methods600 and/or 700 may be implemented by a program for execution by aprocessor such as the processor 812 shown in the example processorplatform 800 discussed below in connection with FIG. 8. A processor issometimes referred to as a microprocessor or a central processing unit(CPU). The program may be embodied in software stored on a tangiblecomputer-readable medium such as a CD-ROM, a floppy disk, a hard drive,a digital versatile disk (DVD), a Blu-ray disk, or a memory associatedwith the processor 812, but the entire program and/or parts thereofcould alternatively be executed by a device other than the processor 812and/or embodied in firmware or dedicated hardware. Further, although theexample program is described with reference to the flowchart illustratedin FIGS. 6, 7A, 7B, 7C, and/or 7D, many other methods of implementingthe example generator brake controller 220 of FIGS. 2, 3, and/or 4 mayalternatively be used. For example, the order of execution of the blocksmay be changed, and/or some of the blocks described may be changed,eliminated, or combined.

As mentioned above, the example methods of FIGS. 6, 7A, 7B, 7C, and/or7D may be implemented using coded instructions (e.g., computer-readableinstructions) stored on a tangible computer-readable medium such as acomputer-readable storage medium (e.g., a hard disk drive, a flashmemory, a read-only memory (ROM), a compact disk (CD), a digitalversatile disk (DVD), a cache, a random-access memory (RAM)) and/or anyother storage media in which information is stored for any duration(e.g., for extended time periods, permanently, brief instances, fortemporarily buffering, and/or for caching of the information). As usedherein, the term tangible computer-readable medium is expressly definedto include any type of computer readable storage medium and to excludepropagating signals and to exclude transmission media. Additionally oralternatively, the example process of FIG. 6 may be implemented usingcoded instructions (e.g., computer-readable instructions) stored on anon-transitory computer-readable medium such as a hard disk drive, aflash memory, a read-only memory, a compact disk, a digital versatiledisk, a cache, a random-access memory and/or any other storage media inwhich information is stored for any duration (e.g., for extended timeperiods, permanently, brief instances, for temporarily buffering, and/orfor caching of the information). As used herein, the term non-transitorycomputer-readable medium is expressly defined to include any type ofcomputer-readable medium and to exclude propagating signals and toexclude transmission media. As used herein, when the phrase “at least”is used as the transition term in a preamble of a claim, it isopen-ended in the same manner as the term “comprising” is open ended.Thus, a claim using “at least” as the transition term in its preamblemay include elements in addition to those expressly recited in theclaim.

The example method 600 of FIG. 6 begins execution when the user beginsoperating the exercise machine 100 (e.g., when rotation of the rotor ofthe generator 405 is detected). However, in some examples, the method600 operates continuously while the exercise machine 100 receives powerfrom the power supply 110.

In the illustrated example, the mode controller 340 receives a userwattage setting (P_(USER TARGET)). (block 605). In the illustratedexample, the P_(USER TARGET) is received from the console 120. In otherexamples, P_(USER TARGET) is calculated from other user input including,for example, a desired heart rate, a desired resistance level, an age, aweight, a desired amount, and/or rate of calories to be burned. However,the P_(USER TARGET) may be received in any other fashion.

The mode controller 340 measures the flyback power supply input current(I_(PS)). (block 610). The mode controller 340 measures a rectifiedgenerator output voltage (V_(BUS)). (block 615). Using the measuredvalues, the mode controller 340 calculates the flyback power supplyinput power (P_(PS)). (block 620). In the illustrated example P_(PS) iscalculated as V_(BUS) times I_(PS).

The mode controller 340 calculates a total load power of the console,including any attachments (P_(L)). (block 625). In the illustratedexample, P_(L) is calculated as the flyback output voltage (V_(O)) timesthe total load current (I_(L)). The mode controller 340 calculates theflyback power supply efficiency (N_(PS)). (block 630). In theillustrated example, N_(PS) is calculated as P_(L) divided by P_(PS),which is the rectified generator output voltage (V_(BUS)) times theflyback power supply input current (I_(PS)). The mode controller 340then calculates the mode limit factor as P_(L) divided by N_(PS) (block635).

The mode controller 340 determines whether P_(USER TARGET) is less thanseven tenths of the mode limit factor. (block 640). If P_(USER TARGET)is less than seven tenths of the mode limit factor, the mode controller340 sets the flyback power supply input current (I_(PS)) equal to theresistance felt by the user measured in watts (P_(USER)) divided by theV_(BUS) (block 645). The mode controller 340 sets the target brakecurrent (I_(B TARGET)) to zero. (block 650).

If P_(USER TARGET) is not less than seven tenths of the mode limitfactor, the mode controller determines whether P_(USER TARGET) is lessthan one and three tenths of the mode limit factor. (block 655). WhenP_(USER TARGET) is not less than seven tenths of the mode limit factorand lesser than one and three tenths of the mode limit factor, the modecontroller 340 sets the flyback power supply input current (I_(PS))equal to seven tenths of the resistance felt by the user measured inwatts (P_(USER)) divided by the V_(BUS) (block 660). The mode controllerthen sets the I_(B TARGET) to a function of P_(USER TARGET), an RPM ofthe rotor of the generator 405, and I_(PS). (block 665).

When P_(USER TARGET) is not lesser than one and three tenths of the modelimit factor, the mode controller 340 sets the flyback power supplyinput current (I_(PS)) equal to seven tenths of the resistance felt bythe user measured in watts (P_(USER)) divided by the V_(BUS), (block670). The mode controller then sets the I_(B TARGET) to a function ofP_(USER TARGET), an RPM of the rotor of the generator 405, and I_(PS).(block 665). Control then proceeds to block 605 where the modecontroller receives the user wattage setting.

The example method 700 of FIGS. 7A, 7B, 7C, and 7D begins execution whenthe user begins operating the exercise machine 100 (e.g., when rotationof the rotor of the generator 405 is detected). However, in someexamples, the method 700 operates continuously while the exercisemachine 100 receives power from the power supply 110. The example method700 illustrates an example wherein the generator brake controller 220does not have separate modes of operation.

The mode controller 340 sets initial control loop variables. (block702). The power supply duty cycle (D_(PS)) of the initial sample is setto one, which results in all electrical power sent to the console 120being sourced from the power supply 110. The brake current duty cycle(D_(BC)) is set to one, which results in no resistance being applied bythe brake. A mechanical constant (MECH) is set based on the type of theexercise machine. In the illustrated example, the exercise machine is abike, and has a mechanical constant of 1.7. However, any othermechanical constant may additionally or alternatively be used. Inaddition, in other examples, any type of exercise machine having thesame or any other mechanical constant may additionally or alternativelybe used. For example, a cross trainer exercise machine may have amechanical constant of 7.184.

The mode controller 340 measures the present brake current I_(BRAKE).(block 704). The mode controller 340 also measures the present powersupply current I_(PS). (block 706). In addition, the mode controller 340measures the present RPM (rotations per minute) value from the generatorpower receiver 320. (block 708). The mode controller 340 determines if aTorque reference value (TORQUE_(REF)) is received from the console 120.(block 710). If TORQUE_(REF) is received from the console, controlproceeds to block 716. If TORQUE_(REF) is not received from the console,control proceeds to block 712, where the mode controller 340 receives adesired wattage value from the console (WATTS_(USER) _(_) _(SELECTED)).(block 712). The mode controller 340 calculates the TORQUE_(REF) usingthe following equation:

TORQUE_(REF)=WATTS_(USER) _(_) _(SELECTED)*63024/(RPM*746)−MECH

In the illustrated example, the above equation is used for differenttypes of exercise machine. However, in some examples, a differentequation may be used to calculate TORQUE_(REF) when a different type ofexercise machine is used. In the illustrated example, the modecontroller 340 calculates the TORQUE_(REF) value. However, in someexamples, the console 120 may calculate the TORQUE_(REF) value andcommunicate the TORQUE_(REF) value to the mode controller 340 via, forexample, a serial bus.

The mode controller determines if TORQUE_(REF) is greater than, forexample, seventeen. (block 716). If TORQUE_(REF) is not greater thanseventeen, the mode controller 340 sets a constant K₀ to, for example,0.8152. (block 718). If TORQUE_(REF) is greater than seventeen, the modecontroller 340 sets the constant K0 to, for example, 0.1. (block 720).The mode controller 340 also sets a power supply constant (K_(PS)), aconstant K₁, and a constant K₂. (block 722). In the illustrated example,KPS is set to, for example, 24.706, K₁ is set to, for example, 5.5528and K₂ is set to, for example, 25.235. In other examples, other constantvalues may be used. The mode controller 340 calculates a torque valueTORQUE_(CALC) (block 724) using the following equation:

TORQUE_(CALC) =K ₀ +K _(PS) *I _(PS) +K ₁ *I _(BRAKE) +K ₂ *I _(BRAKE) ²

The mode controller 340 measures V_(BUS). (block 726) (FIG. 7B). In theillustrated example, V_(BUS) is the rectified generator output voltagereceived from the generator power receiver 320. The mode controller 340determines if a resistance level has been selected via the console 120.(block 728). If the RPM is less than an RPM threshold (block 730), theV_(BUS) is less than a V_(BUS) threshold (block 734), the WATTS_(USER)SELECTED is less than a WATTS_(THRESHOLD) (block 735), or the selectedlevel is zero (block 736), the mode controller sets a power supplyreference current (I_(PS) _(_) _(REF)) to zero amps. (block 732). In theillustrated example, the RPM threshold is, for example, three hundredand sixty rotations per minute, the V_(BUS) threshold is, for example,fifty volts, and the WATTS_(THRESHOLD) is, for example, sixty watts.However, any other threshold values may additionally or alternatively beused. If the RPM is not less than an RPM threshold (block 730), theV_(BUS) is not less than a V_(BUS) threshold (block 734), theWATTS_(USER) _(_) _(SELECTED) is not less than a WATTS_(THRESHOLD)(block 735), and the selected level is not zero (block 736), the modecontroller 340 calculates the power supply reference current (I_(PS)_(_) _(REF)) (block 738) using the following equation:

I _(PS) _(_) _(REF) =K _(HYBRID)*(TORQUE_(REF) −K ₀)K _(PS)

Where K_(HYBRID) is a constant that sets the maximum power that will besupplied from the generator brake controller 220. In the illustratedexample, K_(HYBRID) is, for example, 0.9. However any other value mayadditionally or alternatively be used for K_(HYBRID). If I_(PS) _(_)_(REF) is greater than, for example, 0.55 ampere (block 740), the modecontroller 340 limits I_(PS) _(_) _(REF) to 0.55 ampere (block 742). Themode controller 340 also measures a console voltage (V_(O)). (block744). In the illustrated example, the console voltage is the totalvoltage used by the console including any additional attachments (e.g.,a television, a smartphone, etc.). In addition, the mode controller 340measures a console current (I_(O)). (block 746). In the illustratedexample, the console current is the total current drawn by the consoleincluding any additional attachments (e.g., a television, a smartphone,etc.).

The mode controller 340 determines if I_(PS) _(_) _(REF) is greater thanK_(HYBRID)*I_(O)*V_(O)/(V_(BUS)*P_(SEFF)). (block 748). In theillustrated example, PS_(EFF) is a constant value representing anefficiency of the power supply. In some examples, PS_(EFF) is set to,for example, 0.6. However, any other value for PS_(EFF) may additionallyor alternatively be used. For example, the efficiency of the powersupply may vary based on any other variable such as, for example, aninput voltage, an output current, a load resistance, etc. If I_(PS) _(_)_(REF) is greater than K_(HYBRID)*I_(O)*V_(O)/(V_(BUS)*PS_(EFF)), themode controller 340 sets I_(PS) _(_) _(REF) equal toK_(HYBRID)*I_(O)*V_(O)/(V_(BUS)*PS_(EFF)). (block 750).

The mode controller 340 also calculates an error current (block 752)(FIG. 7C) using the following equation:

I _(PS) _(_) _(ERROR)(t)=I _(PS) _(_) _(REF)(t)−I _(PS)(t)

The mode controller 340 stores the error current value in a memory ofthe mode controller 340. (block 754). Storing the error current valueenables the error current value to be used in subsequent control loopcalculations. The mode controller also calculates a torque error (block756) using the following equation:

TORQUE_(ERROR)(t)=TORQUE_(REF)(t)−TORQUE_(CALC)(t)

The mode controller 340 stores the torque error in the memory of themode controller 340. (block 758). Storing the torque error enables thetorque error value to be used in subsequent control loop calculations.

The mode controller 340 sets proportional gain variables. (block 760).In the illustrated example, a power supply gain (G_(PS)) is set to, forexample, 0.05, and a brake current gain (G_(BC)) is set to, for example,0.0005. However, any other gain values may additionally or alternativelybe used. For example, a different gain value may be used while the brakecurrent is rising compared to when the brake current is falling. Themode controller 340 also sets time constants to be used in subsequentcontrol loops (block 762). In the illustrated example, a power supplytime constant (T_(PS)) is two seconds, and a brake current time constant(T_(BC)) is two hundred milliseconds. However, any other time constantsmay additionally or alternatively be used. The mode controller 340 alsocalculates a power supply duty cycle (D_(PS)) (block 764) using thefollowing equation:

D _(PS)(t)=D _(PS)(t−1)+G _(PS)*(((1+Δt)/T _(PS))*I _(PS) _(_)_(ERROR)(t)−I _(PS) _(_) _(ERROR)(t−1))

In the above equation, D_(PS)(t−1) represents the power supply dutycycle from the previous iteration of calculation. The above equation isan implementation of a proportional integral control equation. However,any other type of control equation may additionally or alternatively beused. In the first iteration of the calculation, the previous powersupply duty cycle is one. In the above equation, Δt is set to twohundred milliseconds. However, any other value for Δt may alternativelybe used. In the above equation, t represents the calculation for thecurrent period, whereas t−1 represents the value of the function (e.g.,I_(PS) _(_) _(ERROR)(t−1)) stored in the previous period. The modecontroller 340 sets the power supply duty cycle via the power outputcontroller 350. (block 766).

The mode controller 340 also calculates a brake current duty cycle(D_(BC)) (block 768) using the following equation:

D _(BC)(t)=D _(BC)(t−1)+G _(BC)*(((1+Δt)/T_(BC))*TORQUE_(ERROR)(t)−TORQUE_(ERROR)(t−1))

In the above equation, D_(BC)(t−1) represents the brake current dutycycle from the previous iteration of the calculation. The above equationis an implementation of a proportional integral control equation.However, any other type of control equation may additionally oralternatively be used. In the first iteration of the calculation, theprevious brake current duty cycle is one. In the above equation, Δt isset to twenty milliseconds. However, any other value for Δt mayalternatively be used. In the above equation, t represents thecalculation for the current period, whereas t−1 represents the value ofthe function (e.g., TORQUE_(ERROR)(t−1)) stored in the previous period.Prior to setting the brake current via the brake controller, the modecontroller clamps the brake current duty cycle to ensure that the userexperiences the desired level of resistance from the exercise machine100. The mode controller 340 calculates a brake current clamp(D_(CLAMP)) (block 770) (FIG. 7D) using the following equation:

D _(CLAMP)=(RPM*0.0313+55.6)/100

In the above equation, the brake current clamp is a function of RPM.However, any other properties, variables, etc. may additionally oralternatively be used in the brake current clamp equation. The modecontroller 340 determines if the brake current clamp is greater than,for example, one (block 772) and, if so, the mode controller 340 setsthe brake current clamp to one. (block 774). If the brake current clampis not greater than one, the mode controller 340 determines if the brakecurrent clamp is less than, for example, 0.55 (block 776). If the brakecurrent clamp is less than 0.55, the mode controller sets the brakecurrent clamp to 0.55 (block 778). The mode controller 340 alsodetermines if the brake current duty cycle is less than the brakecurrent clamp (block 780) and, if so, sets the brake current duty cycleto the brake current clamp. (block 782). If the brake current duty cycleis not less than the brake current clamp (block 780) and/or afterclamping the brake current duty cycle (block 782), the mode controllersets the duty cycle of the brake controller 330 to the brake currentduty cycle. (block 784). Control then proceeds to block 704 (FIG. 7A)where the control loop is repeated.

FIG. 8 is a block diagram of an example processor platform 800 that mayexecute, for example, machine-readable instructions to perform themethods 600, 700 of FIGS. 6 and 7A-D to implement the example generatorbrake controller of FIG. 3. The processor platform 800 can be, forexample, an exercise machine, a personal computer, a mobile phone (e.g.,a cell phone), a personal digital assistant (PDA), or any other type ofcomputing device.

The processor platform 800 of the instant example includes a processor812. For example, the processor 812 can be implemented by one or moremicroprocessors or controllers from any desired family or manufacturer.

The processor 812 includes a local memory 813 (e.g., a cache) and is incommunication with a main memory including a volatile memory 814 and anon-volatile memory 816 via a bus 818. The volatile memory 814 may beimplemented by Synchronous Dynamic Random Access Memory (SDRAM), DynamicRandom Access Memory (DRAM), RAMBUS Dynamic Random Access Memory (RDRAM)and/or any other type of random access memory device. The non-volatilememory 816 may be implemented by flash memory and/or any other desiredtype of memory device. Access to the main memory 814, 816 is controlledby a memory controller.

The processor platform 800 also includes an interface circuit 820. Theinterface circuit 820 may be implemented by any type of interfacestandard, such as an Ethernet interface, a universal serial bus (USB), aserial bus, and/or a PCI express interface.

One or more input devices 822 are connected to the interface circuit820. The input device(s) 822 permit a user to enter data and commandsinto the processor 812. The input device(s) can be implemented by, forexample, a serial port, a keyboard, a mouse, a touchscreen, a track-pad,a trackball, isopoint and/or a voice recognition system.

One or more output devices 824 are also connected to the interfacecircuit 820. The output devices 824 can be implemented, for example, bydisplay devices (e.g., a liquid crystal display, a cathode ray tubedisplay (CRT), a printer and/or speakers). The interface circuit 820,thus, typically includes a graphics driver card.

The interface circuit 820 also includes a communication device such as amodem or network interface card to facilitate exchange of data withexternal computers via a network 826 (e.g., an Ethernet connection, adigital subscriber line (DSL), a telephone line, coaxial cable, acellular telephone system, etc.).

The processor platform 800 also includes one or more mass storagedevices 828 for storing software and data. Examples of such mass storagedevices 828 include floppy disk drives, hard drive disks, compact diskdrives and digital versatile disk (DVD) drives.

The coded instructions 832 of FIG. 6 may be stored in the mass storagedevice 828, in the volatile memory 814, in the non-volatile memory 816,and/or on a removable storage medium such as a CD or DVD.

From the foregoing, it will appreciated that the above disclosedmethods, apparatus and articles of manufacture enable power generated bya user during a workout to be used to power a console of an exercisemachine in parallel with an external power source.

We claim:
 1. An exercise machine comprising: a power receiver to measurea power output by a generator that is to convert movement of a moveablepart into electric power, the power receiver to calculate a rotationsper minute of the moveable part; a mode controller to calculate a powersupply duty cycle based on the power output by the generator, therotations per minute of the moveable part, and a user selected wattage;and a power output controller to control power provided to a console ofthe exercise machine based on the power supply duty cycle.
 2. Theexercise machine as described in claim 1, further including the console.3. The exercise machine as described in claim 1, further including apower supply to receive power from a commercial power source, whereinthe power output controller includes a first rectifier and a secondrectifier in a wired-OR configuration, the first rectifier coupled tothe power supply and the console, the second rectifier coupled to thegenerator and the console.
 4. The exercise machine as described in claim3, wherein the first rectifier is a diode.
 5. The exercise machine asdescribed in claim 3, wherein the first rectifier is a controlledswitch.
 6. The exercise machine as described in claim 3, wherein thepower supply duty cycle is a pulse width modulated signal, and furtherincluding a converter intermediate the second diode and the generator,the converter to receive the pulse width modulated signal.
 7. Theexercise machine as described in claim 6, wherein the converter is anisolated flyback converter.
 8. The exercise machine as described inclaim 6, wherein the converter is a switch.
 9. The exercise machine asdescribed in claim 1, wherein the generator includes an electromagneticbrake controlled by a resistive load.
 10. The exercise machine asdescribed in claim 1, wherein the generator is loaded by a controlledresistive load.
 11. An exercise machine comprising: means for measuringa power output by a generator that is to convert movement of a moveablepart into electric power; first means for calculating a rotations perminute of the moveable part; second means for calculating a power supplyduty cycle based on the power output by the generator, the rotations perminute of the moveable part, and a user selected wattage; and means forcontrolling power provided to a console of the exercise machine based onthe power supply duty cycle.
 12. The exercise machine as described inclaim 11, further including the console.
 13. The exercise machine asdescribed in claim 11, further including power supply means to receivepower from a commercial power source, the means for controllingincluding a first rectifying means and a second rectifying meansarranged in a wired-OR configuration, the first rectifying means coupledto the power supply means and the console, the second rectifying meanscoupled to the generator and the console.
 14. The exercise machine asdescribed in claim 13, wherein the first rectifying means is a diode.15. The exercise machine as described in claim 13, wherein the firstrectifying means is a controlled switch.
 16. The exercise machine asdescribed in claim 13, wherein the power supply duty cycle is a pulsewidth modulated signal, and further including converting meansintermediate the second rectifying means and the generator, theconverting means to receive the pulse width modulated signal.
 17. Theexercise machine as described in claim 16, wherein the converting meansis an isolated flyback converter.
 18. The exercise machine as describedin claim 16, wherein the converting means is a switch.
 19. The exercisemachine as described in claim 11, wherein the generator includes anelectromagnetic brake controlled by a resistive load.
 20. The exercisemachine as described in claim 11, wherein the generator is loaded by acontrolled resistive load.